Syringe



July 18, 1967 J. L. HIGGINS SYRINGE INVEENTOR H59 Z726 Filed July 17, 1965 United States Patent 3,331,538 SYRINGE John L. Higgins, Daytona Beach, Fla., assignor to Roehr Products Company, Inc., a corporation of Delaware Filed July 17, 1963, Ser. No. 295,709 1 Claim. (Cl. 222387) This invention relates to syringes and more particularly to hypodermic syringes.

In the conventional form of hypodermic syringe, the fluid is forced through a bore in the nose piece of the syringe by means of a plunger movable through the barrel of the syringe to a final position wherein the plunger seats on the inner surface of the nose piece. A problem arises in such syringe constructions in that the plunger often sticks to the nose piece due to the formation of a vacuum between the plunger and the transverse wall of the nose piece. One solution to this problem has been to provide some means for breaking the seal between the plunger and the barrel as the plunger approaches the final position, thereby venting the space between the plunger and nose piece outwardly through the barrel. This structure has the obvious defect of wear on the plunger seal and the substantial possibility of leakage of the fluid being forced from the syringe through the broken seal structure.

The present invention comprehends an improved syringe structure eliminating the above discussed plunger sticking problem in a novel and simple manner. Thus, a principal feature of the present invention is the provision of a new and improved syringe structure.

Another feature of the invention is the provision of such a syringe structure having new and improved means for preventing the formation of a vacuum between the plunger and the end wall, or nose, portion of the syringe when the plunger is in the final position.

A further feature of the invention is the provision of such a syringe wherein means are provided on at least one of the plunger and barrel elements for providing a passage from the outlet bore to between the plunger and end wall when the plunger is in the final position.

Still another feature of the invention is the provision of such a syringe wherein the passage providing means comprises a projection on one element extending toward the other element to maintain a spacing therebetween when the plunger is in the final position.

A still further feature of the invention is the provision of such a syringe wherein the passage providing means comprises a groove extending transversely across at least one of the elements and opening toward the other element.

Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a fragmentary diametric section of a syringe of conventional construction;

FIGURE 2 is a fragmentary diametric section of syringe having vacuum preventing means embodying the invention;

FIGURE 3 is a transverse section taken substantially along the line 3-3 of FIGURE 2;

FIGURE 4 is a fragmentary diametric section of syringe having a modified form of vacuum breaking means embodying the invention;

FIGURE 5 is a transverse section taken substantially along the line 5-5 of FIGURE 4;

3,331,538 Patented July 18, 1967 FIGURE 6 is a fragmentary diametric section of a syringe having still another form of vacuum preventing means embodying the invention;

FIGURE 7 is a transverse section taken substantially along the line 77 of FIGURE 6;

FIGURE 8 is a fragmentary diametric section of a syringe having yet another form of vacuum preventing means embodying the invention; and

FIGURE 9 is a transverse section taken substantially along the line 99 of FIGURE 8.

In the exemplary embodiment of the invention as disclosed in FIGURES 2 and 3 of the drawing, a syringe generally designated 10 is shown to comprise a tubular barrel 11 provided at one end with a nose piece generally designated 12 including a transverse, frusto-conical end wall 13 and an axial outwardly extending portion 14. An axial bore 15 extends through the portion 14 and wall 13 to open into the interior of the barrel 11. Fluid is forced outward through the bore 15 from the barrel 11 by means of a plunger 16 carried on the end of an actuator 17 extending coaxially through the barrel. The plunger may be formed of a resilient material, such as rubber, and is provided with a plurality of annular peripheral bosses defining sealing means 18 for removably, sealingly engaging the barrel 11 and thereby causing the plunger to act as a piston in forcing the fluid outwardly through the nose portion 12. The outer end of the plunger is defined by a conical head 19.

Referring now to FIGURE 1, a problem arises in the conventional syringe structures having the above described construction in that a vacuum condition may develop in the space V between the head H and the end wall E when the plunger P is moved to its final position. This vacuum results from the sealing engagement of the head with the end wall circumjacent the bore B and the engagement of the sealing means S with the tubular barrel T when the user attempts to withdraw the plunger from the final position. Thus, the plunger is held in the position of FIGURE 1 eifectively precluding withdrawal thereof for subsequent use of the syringe.

In the syringe structure 10 of the present invention, means are provided for eliminating the above described vacuum condition by providing a passage from the bore 15 to between the head 19 and the end wall 13 when the plunger 16 is in the final position. More specifically, as shown in FIGURES 2 and 3, the head 19 is maintained in spaced relationship to the end wall 13 by means of a plurality of projections 2% herein comprising ribs on end wall 13, extending transversely, or outwardly, from the bore 15. Thus, the spaces 21 between the ribs 20 define passages providing communication between the bore 15 and the space 22 between the plunger head 19 and the end wall 13. Resultingly, the space 22 is vented to the bore 15 and a vacuum condition is efiectively precluded in space 22 notwithstanding the full movement of the plunger to the final position of FIGURE 2. As the annular sealing means 18 are in no way affected by the vacuum breaking structure of syringe 10, the useful life thereof is elfective- 1y maximized and leakage of the fluid being ejected back beyond the sealing means is effectively precluded.

Turning now to the embodiment of FIGURES 4 and 5, a syringe generally designated is shown to comprise a syringe generally similar to that of syringe 10 but having an end Wall 113 provided with transverse or outwardly extending grooves 120 in lieu of the ribs 20 of syringe 10. Grooves 120 function similarly, however, in defining passages providing communication between the bore 115 and the space 122 between the plunger 116 and the end wall 113 when the plunger is in the final position illustrated in FIGURE 4.

Turning to FIGURES 6 and 7, still another modified form of syringe generally designated 210 is shown to comprise a syringe generally similar to syringe but having a plurality of projections 220 provided on the head 219 of the plunger 216 extending therefrom toward the end wall 213 of the barrel 211 to maintain communication between the bore 215 and the space 222 between the head 219 and the end wall 213 when the plunger is in the final position of FIGURE 6. As best seen in FIGURE 7, the projections 220 may comprise embossed markings, herein numerals. Such markings, for example, may be used for identification purposes.

In the form of the invention illustrated in FIGURES 8 and 9, the syringe 310 is provided with a head 319 of the plunger 316 having an axial passage 320 extending from the tip 319a of the head which communicates with the bore 315 when the plunger is in the final position of FIG- URE 8. A plurality of side passages 320a extend radially outwardly from passage 320 to space 322 to provide communication between the bore 315 and space 322 in the final position of the plunger illustrated in FIGURE 8.

Thus, the invention comprehends broadly the provision on at least one of the plunger and end wall elements of the syringe of means providing a passage from the bore of the nose piece of the syringe through the space between the plunger and the end wall when the plunger is in the final position thereby to preclude formation of a vacuum therebetween. The invention comprehends the provision of such vacuum preventing means in the form of projections on either or both of the plunger and end Wall elements, such projections comprising selectively ribs, embossments in the form of markings or numerals, etc., and all forms of projections providing a maintained spacing between the plunger and end wall to assure communication from the space therebetween to the bore of the nose piece. Alternatively, the invention comprehends the provision of grooves in one or both of the plunger and end wall elements to provide the desired communication to the nose piece bore. Still further, alternatively, the invention comprehends the provision of such vacuum preventing means in the form of passages through the body of 'one or both of the plunger and end wall to maintain the desired communication to the bore of the nose piece.

Thus, the different forms of syringes illustrated in FIG- URES 2 through 9 are similar to each other except as specifically indicated. Similar elements of the different syringes are identified by similar numerals except having diiferent hundred prefixes corresponding to the hundred designation of the syringe.

In use, the syringes of the present invention function in the normal manner except that upon reaching the final position any tendency for sticking is eliminated permitting free retraction of the plunger therefrom as desired. The sealing means of the syringes disclosed herein remain unbroken as the venting of the space between the plunger and end wall is effected to the bore of the nose rather than by deformation of the sealing means to provide a vent therearound as has been done in the past. Thus, the syringe of the present invention comprises an improved simple and economical structure having long trouble-free life while yet effectively precluding the vexatious problem of the sticking of the plunger in the final position.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as defined in the appended claim.

I claim:

In a syringe, a barrel element having a transverse end wall with an outlet bore therethrough, a plunger element movable through the barrel to a final position wherein the plunger is juxtaposed to the end wall, said plunger element having peripheral means movably sealing the plunger to the barrel, and a passage through one of said elements providing communication from said bore to the space between said plunger and said end wall when said plunger is in said final position to preclude formation of a vacuum therebetween, said passage comprising an axial portion in said plunger and a radial portion extending from said axial portion outwardly to said space.

References Cited UNITED STATES PATENTS Re. 17,059 8/1928 Hein l28--218 2,098,106 11/1937 Pieck 222-389 X 2,798,487 7/1957 Ferguson 128-2l8 RICHARD A. GAUDET, Primary Examiner.

ROBERT E. MORGAN, Examiner. 

